Cisco :: 2504 Upgrading / Growing Our Wi-Fi Network

We are planning for a modest expansion of our wifi network.  Here is what we currently have, and what we are doing:
 
-2 1100 B/G AP's; a "primary" and a repeater.  Both have a single SSID. 
 
-1 1142 B/G/N; autonomous, with a different SSID
 
What we would like to do:
 
-Purchase a 2504 WLC and two more AP.  Looking at a 3602 simply for future growth, but are not sold on the idea of such an AP.  Would consider two more 1142.  At any rate, we are looking for two more AP. 
 
-Still keep our current AP's in use.

-Is a 5 access point wifi network, all controlled by a 2504 feasible?
 
-Will our existing investment of older 1100's and the single 1142 play nice with eiither a pair of 3600 (or 3500 or even 1142)?
 
-Can we go to a single SSID using all of this equipment, and clients connect at whatever speed is possible with whatever AP they are joined with?